This invention relates generally to microwave antenna structures and, more particularly, to phased array antennas requiring a large number of power combiners or dividers. Microwave power combiners and dividers using hybrid techniques are difficult to design and construct, as well as being heavy and relatively costly. Microstrip or stripline power combiners are too lossy in the millimeter-wave frequency range, and additional amplifiers are often needed for compensation. The addition of these amplifiers not only increases the system complexity and cost, but also lowers the manufacturing yield, increases heat losses, and reduces system reliability. Therefore, there is a need for a simpler, more reliable, and less costly technique for combining and dividing microwave power in a beamforming antenna structure.
A related problem in the phased array antenna field is a difficulty that exists in constructing a phased array antenna system in the millimeter-wave frequency range. Such structures have been impractical because of system complexity and cost. A high-gain phased array requires a large number of microwave feeds, beam steering electronics, and labor-intensive manufacturing and testing. Moreover, even if these difficulties can be overcome the resulting device consumes excessive power and produces intolerable heat, due to low receiver or transmitter efficiency. Components and devices have been successfully developed for operation in the X-band and Ku-band of frequencies, which fall into the centimeter-wave or supra-high frequency (SHF) range. However, attempts to scale these for operation in the extra-high frequency (EHF) or millimeter-wave range have not been fruitful because of intolerably high radio-frequency (rf) losses, and difficulties in manufacturing precision and packaging. Therefore, there is still a need for improvement in the technology used for millimeter-wave phased arrays.